May/June 2003 Table of Contents
T. Joseph W. Lazio
programs have picked up tantalizing radio signals. Could some of
these signals represent genuine transmissions from ET?
who has experienced a momentary disruption in a cell phone conversation
knows that the first task is to verify that the other party is still
on the line. Researchers who search for extraterrestrial intelligence
(SETI) have found themselves in a similar situation. On a number
of occasions they have appeared to be on the tantalizing brink of
making first contact with another civilization, only to be unable
to verify whether they have found a real signal.
instance, in August 1977 the Ohio State University "Big Ear"
radio telescope picked up what appeared to be a booming ET transmission.
Project volunteer Jerry Ehman, who first noticed the powerful signal
on a computer printout, was so excited that he scribbled "Wow!"
on the paper record of the observation.
recently, the Planetary Society's Megachannel Extraterrestrial Assay
(META) SETI project, operated by Paul Horowitz and colleagues at
the Oak Ridge Observatory in Massachusetts, picked up 11 transmissions
that exhibit all the hallmarks of being genuine ET signals. Intriguingly,
these 11 candidate transmissions tended to be located in or near
the plane of the Milky Way's disk, just as one might expect if the
transmissions originated from stars in our galaxy.
all attempts to verify these META candidates or the Wow! signal
(or similar candidates from other SETI programs) have failed. As
Carl Sagan wrote, "Extraordinary claims require extraordinary
evidence." Without more evidence, SETI researchers are unwilling
to cite these candidates as evidence of ET transmissions. Before
dismissing these candidates too hastily, however, we should consider
whether they might represent real ET transmissions that were not
subsequently verified because they were modified en route to Earth.